Infrared spectroscopic characteristics of mixed rare earth triple-decker complexes with phthalocyaninato and 5-(4-hydroxyphenyl)-10,15,20-tris(4-octyloxy)porphyrinato ligands

The infrared (IR) spectroscopic data for a series of nine mixed rare earth triple-deckers M2III[TO(OH)PP](Pc)2] [M = La⋯Dy, except Pm, Y and Ho⋯Lu; H2Por = 5-(4-hydroxyphenyl)-10,15,20-tris(4-octyloxyphenyl)porphyrin, Pc = unsubstituted phthalocyanine] with tervalent rare earths have been collected. For M2III[TO(OH)PP](Pc)2], typical IR marker bands for the unsubstituted phthalocyanine dianion Pc2− are strong bands at 1327–1329 cm−1, and a weak band around 1370–1383 cm−1. They can be assigned to pyrrole CC stretchings. The absence of Pc2− another marker IR band around 1376 cm−1 demonstrates that the cerium metal ion in the IR spectrum of Ce2III[TO(OH)PP](Pc)2] exists as intermediate valence state between III and IV. The IR spectra of these mixed triple-decker complexes reveal that the frequencies of pyrrole stretching, isoindole breathing, and aza stretchings are decreased sensitive to the rare earth ionic size, and remain basically unchanged along with the lanthanide contraction. These facts indicate that the π–π interactions in these mixed triple-deckers are weaker than those in the double-deckers.

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► The IR spectra of nine triple-deckers have been systematically investigated.
► Most of the IR frequencies are decreased sensitive to the rare earth ionic size.
► The π–π interactions are weaker than those in the double-deckers.